With the advent of the Internet and a decline in computer prices, many people are communicating with one another through computers interconnected by networks. A number of different communications mediums have been developed to facilitate such communications between computer users. A prolific communication medium is electronic mail (e-mail).
Email participants seem to receive an ever increasing number of mass, unsolicited, commercial e-mailings (colloquially known as e-mail spam or spam e-mail). Spam e-mail is akin to junk mail sent through the postal service. However, because spam e-mail requires neither paper nor postage, the costs incurred by the sender of spam e-mail are quite low when compared to the costs incurred by conventional junk mail senders. Consequently, e-mail users now receive a significant amount of spam e-mail on a daily basis.
Spam e-mail impacts both e-mail users and e-mail providers. For e-mail users, spam e-mail can be disruptive, annoying, and time consuming. For e-mail and network service providers, spam e-mail represents tangible costs in terms of storage and bandwidth usage, which costs are not negligible due to the large number of spam e-mails being sent.